Bench TalkBench Talk for Design Engineers | The Official Blog of Mouser Electronicshttps://www.mouser.com/blogWhat We Learned About EV Range Anxietyhttps://www.mouser.com/blog/what-we-learned-ev-range-anxietyAll,Automotive,Connectors,General,Motor Control,PowerSat, 29 Feb 2020 01:27:50 GMT<p><img alt="Tesla Level 3 EV chargers at a municipal airport " src="/blog/Portals/11/Cummings-EV_Range_Anxiety_themeimage.jpg" style="width: 650px; height: 488px;" title="Tesla Level 3 EV chargers at a municipal airport " /></p>
<p><em><small><strong>Figure 1</strong>: A municipal airport provided Tesla Level 2&nbsp;EV chargers for our return trip. The low-level charging units provided about 80 miles in a two-hour session. (Source: Author)</small></em></p>
<p>I doubt that American explorers Lewis and Clark worried about range anxiety. But I&#39;m sure they, too, would&#39;ve been anxious if they had to navigate an electric vehicle (EV) through an EV charger wilderness.</p>
<p>First off, let me introduce myself and my wife, Brigitte, as proud owners of a 2019 Tesla Model 3. We&#39;ve fully consumed the Kool-Aid on all that&#39;s Tesla. We&rsquo;re Elon Musk fanboys, and we realize the disdain that comes with that claim. Nine months into ownership, our Tesla has lived up to its hype. We&#39;ve had no complaints.</p>
<p>But we just endured the biggest adventure of our Tesla commitment ... a long-distance journey, an 853km (530-mile) roundtrip in an EV equipped with a 50kW battery that has a 362km (225-mile) range between full charges. Maybe not Lewis and Clark challenging, but a challenge nonetheless.</p>
<p>We had heard all about range anxiety. We learned exactly how it truly relates to EV owners who must navigate areas where the EV charging infrastructure hasn&#39;t caught up with demand. It&#39;s a thing.</p>
<p>Oh, we&#39;d taken our Tesla on 483km (300-mile) roundtrips within Texas, but a Level 3 Tesla Supercharger station was midway and on both ends of the trip. No sweat.</p>
<p>Typically at a Tesla Supercharger station in urban settings, it&rsquo;s like an oasis. You&#39;ll find owners stepping away while their cars charge to also connect socially. As we&rsquo;re known to do, Tesla owners will passively brag about their cars and move along with their full charge within 30 minutes.</p>
<p>A few times, however, I&#39;d heard their accounts of range anxiety, about how they had to drastically alter their trip just to reach a specific charging station.</p>
<p>In plotting our trip through a bordering state, the itinerary listed only one Tesla Supercharger station (480V<sub>DC</sub>). From there, well, good luck.</p>
<p>Other <a href="https://www.mouser.com/applications/evs-meeting-charging-station-demand/" target="_blank">Level 3&nbsp;charging stations (not specific to Tesla vehicles)</a> were available in small towns along the way, but the financial or time commitment at these stops or whether they even work were unknown factors during the planning stage (<strong>Figure 2</strong>). Other variables included tire pressure, weather, landscape, and speed limits. We even solicited tips via Tesla owner groups on social media.</p>
<p>We were in for an experience.</p>
<p><img alt="CHAdeMO charging station" src="/blog/Portals/11/Cummings_EV%20Charging%20Pump-min.jpg" style="width: 650px; height: 434px;" title="CHAdeMO charging station" /></p>
<p><em><small><strong>Figure 2</strong>: Many charge stations feature the CHAdeMO nozzle, but Tesla drivers should remember to make sure a nozzle adapter is available. (Source: Kevin McGovern/Shutterstock.com)</small></em></p>
<div>
<h1>The Journey</h1>
</div>
<p>To our surprise, the trip wasn&#39;t overly problematic, but we encountered bouts of range anxiety. Before we left, we charged overnight on our home charger and the next day topped off the charge at a Tesla Supercharger station in a suburb about 64km (40-miles) away. This full charge would take us more than half the distance, ideally all the way. But the range reading on our Tesla dash indicated that we would need additional power to complete the trip. So we stopped off in a small town where a taxi service had a fleet of EVs and made its charging stations available to the general public. Trouble was, we hadn&#39;t counted on needing a CHAdeMO charging adapter. We had a set of Tesla charging adapters, but none that accommodated the CHAdeMO (short for CHArge de MOve) nozzle, which was available for purchase. This was faulty research on our part. Luckily, the business loaned its adapter to us. We downloaded the appropriate app and were able to get a charge just enough to reach our destination. We later found out that this loan was crucial to our trip, otherwise, we would&#39;ve had to wait for hours using mere Level 1 NEMA outlets (standard 120V<sub>AC</sub> outlet with a NEMA rating).</p>
<p>As for the return, our pre-trip research found that our hotel had charging stations. In our favor, they were similar to the ones where we used earlier in the trip. But, we soon realized the adapters we had did not fit the chargers&rsquo; nozzles and, because these chargers were free-standing, that meant there was no friendly business owner available to loan us the appropriate adapter. (Cue the range anxiety.) A quick internet search found free-standing Tesla Wall Connectors at a nearby municipal airport, which took us along pothole-marred rural roads. The chargers, however life-saving, offered a maximum power of 40 amps, which meant 40km (25 miles) of range for every hour of charging. It was our last resort. (Range anxiety is on high). We spent two hours accumulating enough juice to get us back to the taxi service that offered loaner adapters with its charging stations. We limped to that station with 25km (16 miles) of range left, which our car let us know ahead of time. There, we again borrowed the CHAdeMO adapter and got a full charge in about two hours, enough to get us back to the same suburban power units where we topped off the day before. The final cost: $21.32 (US dollars) for the Level 2 chargers and $9.62 (US dollars) for the Tesla chargers. So, a $30.94 (US dollars) power cost for an 853km (530-mile) roundtrip, not counting home charging. Ordinarily, the trip would&rsquo;ve required about 75 liters (20 gallons) of gasoline for an internal combustion engine. So, we counted some savings to compensate ourselves for the range anxiety.</p>
<div>
<h2>Conclusion</h2>
</div>
<p>The personal takeaway: Be prepared with proper adapters. Tesla provides an adapter kit with various connectors, but none that interfaces with a CHAdeMO adapter.&nbsp;</p>
<p>The overall takeaway: <a href="https://www.mouser.com/applications/building-ev-infrastructure/">The EV charging infrastructure has blind spots. We knew that.</a> But in this case, and going forward, we don&#39;t expect that to last long. Already, ChargePoint and the National Association of Truck Stop Operators announced a $1 billion (US dollars) charging collaborative to drive the expansion of EV charging stations along highways and in rural communities. On our particular trip, the roadways still give way to passing motorists and commercial truckers who will be driving more EVs between major cities. For us, the trip was an adventure, but we were glad it was over, perhaps like Lewis and Clark were relieved that their exploration was complete.</p>
1345Solving BLDC Controller Design Challenges with the Qorvo PAC5556https://www.mouser.com/blog/solving-bldc-controller-design-challenges-qorvo-pac5556All,Industrial,Motor Control,PowerWed, 27 Nov 2019 04:52:00 GMT<p><img alt="Qorvo PAC5556 Power Application Controller IC " src="/blog/Portals/11/Huntley_Qorvo_Theme%20Image.jpg" style="margin-left: 10px; margin-right: 10px; float: left; width: 250px; height: 182px;" title="Qorvo PAC5556 Power Application Controller IC " /></p>
<div>
<h2>Brushless Motors Gain Traction</h2>
</div>
<p>Brushless DC (BLDC) motors have become the default choice of motor for a wide range of battery and line-powered equipment and appliances. More reliable and requiring significantly less maintenance than their brushed DC motor counterparts, brushless DC motors have also benefited from a broader industry understanding of how to control them using simple microcontroller algorithms. In today&rsquo;s complex and sophisticated control applications, brushed motors also create too much electrical noise, which means designers need to employ substantial electromagnetic immunity mitigation techniques. Audible noise from brushed motors is also now considered undesirable, particularly for portable battery-powered appliances such as vacuum cleaners and personal power tools, including jigsaws and drills/drivers.</p>
<p>Manufacturers construct brushless DC motors using fixed permanent magnets on the rotor drive shaft and a series of field windings (typically three) on the inside of the motor casing. Switching the current through the three field windings in sequence results in rotation of the drive shaft. Controlling the pulse width and the switching frequency of the drive to each field coil provides control of motor speed, acceleration, and output torque. A closed-loop feedback of the rotor&rsquo;s operation to the three-phase motor control algorithm is required to closely monitor and control the current state of the drive shaft&rsquo;s rotation. The two most popular methods of providing this feedback are:</p>
<ul>
<li>Affixing an encoder disk or other form of rotational sensor to the rotor shaft.</li>
<li>Sensing the back electromagnetic field induced by the rotor&rsquo;s permanent magnets within the field windings. Field-oriented control (FOC) refers to using the induced field voltage.</li>
</ul>
<p>A sensorless method helps improve overall motor reliability as well as reducing the bill of materials (BOM) cost.</p>
<h2>The Architecture of a BLDC Motor Controller</h2>
<p>As discussed in the section above, there are three distinct circuit functions required for a brushless motor controller. These three distinct circuit functions are achieved through:</p>
<ul>
<li>A microcontroller that runs the motor control algorithm</li>
<li>Pulse Width Modulation (PWM) circuitry that provides the switching signals</li>
<li>A power output stage that drives the motor</li>
</ul>
<p>An analog-to-digital function converts the shaft rotational sensor signals into the digital domain for processing by the microcontroller. When designing an embedded motor controller, there are several design considerations. The initial factors that help shape the overall design of an embedded motor controller are:</p>
<ul>
<li>The power/torque required</li>
<li>The power supply source</li>
<li>The shaft speed</li>
</ul>
<p>Today&rsquo;s fast-paced prototype-to-production focus tends to dissuade design engineers from developing a custom controller using discrete parts. Thus, the more popular design route is to use an off-the-shelf microcontroller to run the control algorithm. Most microcontrollers incorporate a wide range of ADC/DAC conversion functions in addition to different peripheral interface options, clocks, and timers. A suitably equipped microcontroller might provide the majority of the required circuit functions, but many microcontrollers tend not to be optimized for motor control&nbsp;applications or incorporate the necessary half/full &ldquo;H&rdquo; bridge motor drive functions. Also, energy management is a necessary function of most applications today and is especially important in motor control applications where the energy efficiency rating is usually a key selection criterion for customers. Power management ICs are available, but this requires the engineering team to integrate another IC into the design, increasing the BOM cost and board space requirements.</p>
<p>As more consumer and industrial motor-based appliances adopted a brushless DC motor design, the need for a device that includes all of the necessary functions drove Qorvo to develop a full-featured power application controller (PAC<sup>&trade;</sup>). Qorvo&rsquo;s <a href="https://www.mouser.com/new/qorvo/active-semi-pac5556-controller/" target="_blank">PAC5556 Power Application Controller<sup>&reg;</sup> (PAC<sup>&trade;</sup>) </a>integrates all the required analog, power management, and gate drive signal sources within a single, compact package.</p>
<div>
<h2>Introducing the Qorvo PAC5556</h2>
</div>
<p>The Qorvo PAC5556 Power Application Controller<sup>&reg;</sup> (PAC<sup>&trade;</sup>) is supplied in a slim QFN-52 package, can operate motors up to 600V<sub>DC</sub>, and incorporates a comprehensive set of features and functions necessary for any BLDC or smart energy application (<strong>Figure 1</strong>). The highly integrated PAC architecture makes the Qorvo PAC5556 especially well-suited for applications where the PCB is shrinking, such as white goods, compressors, and power tools.</p>
<p><img alt="Simplified functional block diagram of the Qorvo PAC5556" src="/blog/Portals/11/Huntley_Qorvo_Solving%20BLDC%20Controller%20Design%20Challenges_Figure%201.jpg" style="width: 600px; height: 539px;" title="Simplified functional block diagram of the Qorvo PAC5556" /></p>
<p><em><small><strong>Figure 1</strong>: The image provides a simplified functional block diagram of the Qorvo PAC5556 power application controller. (Source: Qorvo)</small></em></p>
<p>A 150MHz 32-bit Arm&reg; Cortex&reg;-M4F microcontroller core with 128kB of user-programmable FLASH memory is at the heart of the device. A nested vectored interrupt controller (NVIC), capable of accommodating up to 25 external interrupts, provides a wake-up function to enable the device to come back from different sleep modes. Clock-gating of the 24-bit real-time clock permits low-power operation. The microcontroller unit (MCU) also incorporates a high-speed 12-bit ADC. Configured for little endian operation, PAC5556&rsquo;s Arm&reg; Cortex&reg;-M4F microcontroller core includes hardware support for multiplication and division, DSP instructions, and an IEEE754 single-precision Floating Point Unit (FPU). The integrated FPU supports complex high-resolution control algorithms, such as the ones used with&nbsp;FOC. The high-performance features of this MCU enable design engineers to easily implement complex real-time algorithms, safety software, and diagnostics in their applications.</p>
<p>A pulse-width modulation (PWM) engine provides the drive signals for the motor gate drivers. Capable of fine motor control, down to 10ns, the PWM engine consists of four 16-bit timers and 14 channels.</p>
<p>The analog front end of the PAC5556 is highly configurable and offers both differential and single-ended programmable gain amplifiers, ten comparators, 10-bit DACs, programmable over-current protection, integrated VM ADC sampling, and I/Os for inter-connectible and programmable signal sampling, feedback amplification, and sensor monitoring of multiple analog input signals. These analog capabilities make the device suitable for use in field-oriented control or sensor-based BLDC control applications.</p>
<p>Other salient attributes of the Qorvo PAC5556 include a configurable power manager and application-specific power drivers. The configurable power manager contains a multi-mode switching supply converter that permits the IC and the motor drive circuits to be powered using a buck converter topology. On-chip linear regulators provide the IC supply rails, and the power management functions control the available sleep and hibernate modes. Designers can optimize the power manager for run-time and standby modes. PAC&rsquo;s very small standby current results in very good battery life in battery-powered tools when not in use. In equipment that is always connected to an AC (like white goods), the power manager can help with ENERGY STAR ratings. The power driver block provides all the necessary high- and low-side gate drivers suitable for use in a variety of different motor drive configurations, including half-bridge and full &ldquo;H&rdquo; bridge.</p>
<p>A simplified diagram of the Qorvo PAC5556 used to drive a BLDC motor is illustrated in <strong>Figure 2</strong>.</p>
<p><img alt="simplified diagram of a Qorvo PAC5556" src="/blog/Portals/11/Huntley_Qorvo_Solving%20BLDC%20Controller%20Design%20Challenges_Figure%202.jpg" style="width: 600px; height: 526px;" title="simplified diagram of a Qorvo PAC5556" /></p>
<p><em><small><strong>Figure 2</strong>: The image provides a simplified diagram of a Qorvo PAC5556 used to control a BLDC motor. (Source: Qorvo)</small></em></p>
<p>To aid the prototyping and development process, an evaluation board based around the Qorvo PAC5556 is available. The <a href="https://www.mouser.com/new/qorvo/active-semi-pac5556evk1-dev-kit/" target="_blank">Qorvo PAC5556EVK1</a>&nbsp;is a complete fully-featured evaluation and prototyping platform for the PAC5556 (<strong>Figure 3</strong>). The evaluation board supports gate driving for up to three half H-bridge inverters with ratings up to 220V<sub>AC</sub> or 450V<sub>DC</sub>. A virtual COM port connection to a computer together with a GUI-based software suite permits configuration and control of any application running on the PAC5556EVK1.</p>
<p><img alt="Qorvo PAC5556EVK1 evaluation board" src="/blog/Portals/11/Huntley_Qorvo_Solving%20BLDC%20Controller%20Design%20Challenges_Figure%203.jpg" style="width: 600px; height: 457px;" title="Qorvo PAC5556EVK1 evaluation board" /></p>
<p><em><small><strong>Figure 3:</strong> The Qorvo PAC5556EVK1 evaluation board. (Source: Qorvo)</small></em></p>
<h2>Conclusion</h2>
<p>Brushless DC motors have become a popular choice for use in a wide range of consumer and industrial appliances. As brushless motors are incorporated into a broader range of applications, the ability to quickly design, prototype, and test motor controllers is key to speeding the overall product design process. As a result, design engineers need a device that integrates all the required analog, power management, and gate drive signal sources within a single package. The highly integrated Qorvo PAC5556 Power Application Controller meets the need for a compact power control solution that reduces energy consumption, bulk, and noise in consumer and industrial motor applications. This design also meets tighter board space requirements and keeps the BOM cost to a minimum.</p>
1260Taking a Different Spin on Motor Driver Technology: Enjoy the Ridehttps://www.mouser.com/blog/taking-different-spin-motor-driver-technologyAll,Motor ControlFri, 29 Mar 2019 19:48:33 GMT<p><img alt="Ferris wheel at Navy Pier in Chicago" src="/blog/Portals/11/Golata_STMicroelectronics_Taking%20a%20Different%20Spin_Theme%20Image_1.jpg" style="margin-left: 10px; margin-right: 10px; float: left; width: 250px; height: 167px;" title="Ferris wheel at Navy Pier in Chicago" />I love Ferris wheels. For me, the bigger and higher the Ferris wheel, the better. I love their slow, controlled, graceful spinning. They are big wheels spun and controlled by a big motor. The Ferris wheel derives its name from civil engineering inventor George Washington Gale Ferris Junior who created it for the 1893 Chicago World&rsquo;s Columbian Exposition.</p>
<p>The last time I traveled to Chicago with my wife, I took her to Navy Pier to ride the Ferris wheel. I took her up at night when the city was ablaze in the beauty of the lighted skyline. Sitting high atop the Ferris wheel and looking over the night skyline of downtown is a perfect way to literally sweep your wife off her feet.</p>
<p>I have four daughters. The second daughter&rsquo;s name is Jessie. Jessie and I are alike in a lot of ways, but not about Ferris wheels. Ferris wheels have never been her favorite thing. To her, they are big, scary, rickety, and did I mention big? When Jessie was around five-years-old, our family went to a carnival. Her older sister and her friend were amused by the lights, sounds, and the enormity of the Ferris wheel. Her sister begged my wife and me to let these three ride the Ferris wheel themselves, unaccompanied by adults. Jessie pretended to feel the same amount of excitement.</p>
<p>The three of them got into the cart and took off&mdash;slowing disappearing into the sky with my wife and me watching from below. Jessie watched as we turned into the size of ants below. The cart rocked back and forth as the others swung their legs and arms out of the cart with glee. Jessie clung to the railing in front of her. All she could picture was that movie scene from <em>Mighty Joe Young</em> when the Ferris wheel burst into flames with a little boy stuck at the tippy top. The gorilla came out of nowhere and was the only one who could climb up to save him! JESSIE WANTED DOWN! IMMEDIATELY!</p>
<p>She begged her sister and her friend not to move a millimeter and started yelling for the conductor to get her down. Getting off the ride, she practically kissed the ground. She quickly ran over to me and explained how terrible, unsafe, and unamusing the experience was.</p>
<p>But me, being dad, grabbed her by her hand and took her back on the Ferris wheel to get her over the fear. I was thinking that maybe with me by her side to encourage her and steady her, she would get over it and not add another phobia to her list. Now an adult and married, Jessie is still afraid of Ferris wheels.</p>
<div>
<h2>From Ferris Wheels to Motors</h2>
</div>
<p>While I cannot control people&rsquo;s fears from spinning completely out of control on a Ferris wheel, as an engineer I can help people stay in control by accurately controlling spinning motors. Electric motors convert electricity into mechanical energy. They do so by applying an electric field&mdash;either AC or DC&mdash;to magnets, thereby creating an electromagnetic field. An excellent design employing high-quality motor drivers&mdash;the electronic components responsible for controlling the electric currents applied to motors&mdash;ensures electric motors perform for their application.</p>
<p><a href="https://www.mouser.com/stmicroelectronics/" target="_blank">STMicroelectronics</a> (ST), a pioneer in the field of motor and motion control, provides an extensive range of <a href="https://www.mouser.com/new/stmicroelectronics/stm-stspin-motor-drivers/" target="_blank">motor drivers</a> covering the requirements of stepper motors, brushed DC motors, and brushless DC motors with a wide range of voltage and current ratings (<strong>Figure 1</strong>).</p>
<p><img alt="STMicroelectronics Logo" src="/blog/Portals/11/stmicroelectronics_Logo.jpg" style="width: 200px; height: 90px;" title="STMicroelectronics Logo" /></p>
<p><small><strong><em>Figure 1:</em></strong></small><em><small> STMicroelectronics is a market leader in the design and manufacture of motor drivers.&nbsp;(Source: STMicroelectronics)</small> </em></p>
<div>
<h2>STSPIN Motor Drivers</h2>
</div>
<p>ST offers a comprehensive range of motor drivers, covering all motor types, under their <a href="https://www.mouser.com/new/stmicroelectronics/stmicroelectronics-stspin-drivers/" target="_blank">STSPIN Motor Drivers</a> product family. The STSPIN Motor Drivers support three common motor driver categories:</p>
<p>&nbsp;</p>
<ul>
<li>Stepper motor drivers are scalable and robust devices featuring accurate positioning and a smooth motion profile with up to 256 micro-steps per step.<br />
&nbsp;</li>
<li>Brushed DC motor drivers offer a simple, reliable, and cost-effective solution to drive one or more brushed DC motors over a wide current and voltage range.<br />
&nbsp;</li>
<li>Brushless DC (BLDC) motor drivers provide extensive diagnostics and are fully protected to reduce the number of external components, cost, and complexity.</li>
</ul>
<p>&nbsp;</p>
<p>The <a href="https://www.mouser.com/news/stmicroelectronics-stspin-ebook/mobile/index.html" target="_blank">STSPIN Motor Control</a> family provides industry-leading motor drive performance integration and efficiency in a variety of applications. A complete ecosystem of evaluation and development tools supports developers in the design phase and shortens time-to-market.</p>
<div>
<h2>Applications</h2>
</div>
<p>I am no expert on Ferris wheel motors. However, I do know that all motor categories mentioned previously are found ubiquitously throughout our lives in industrial, office, home, and city applications. Let us look at some of the ways motor drivers help out.</p>
<p>&nbsp;</p>
<ul>
<li>In battery-powered applications, a wide selection of Integrated Circuits (ICs) with energy-saving and ultra-miniaturized form factors is readily available. Motor drivers used to control drones, including gimbal and electronic speed control (ESC), are developed with the objectives of modularity, scalability, and robustness offering extended battery life and precise camera stabilization. Fans and pumps in office and industrial applications run robustly with maximum efficiency and reliability thanks to a comprehensive set of protection and diagnostic features.</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>In applications such as home and office automation, the motor drivers have embedded into them all the functions needed to drive motors efficiently and with high-power density and the highest accuracy. Industrial automation calls for and relies on comprehensive built-in protection and diagnostic schemes to help attain the level of long-term reliability and robustness to cope with harsh factory automation environments.</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>Point-of-sale, ATMs, and vending machine applications benefit from the adaptive current decay control scheme used in many of the STSPIN motor driver ICs. Power tools are enabled by a wide range of power ratings and motor types, as well as varied system partitioning with delocalized diagnostics with high-efficiency and robustness. Printers take advantage of innovative voltage mode driving used in micro-stepping motor drivers that control accuracy and thus motion smoothness for fast, precise, and silent plug-and-play solutions.</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>Robotics and factory automation gain from torque and precision control with the inclusion of an advanced motion profile generator to relieve the host microcontroller. Security and surveillance applications enjoy a wide choice of solutions to fit different requirements and system architectures in a variety of space-saving, thermally optimized packages.</li>
</ul>
<p>&nbsp;</p>
<p>Engineers can use the STSPIN Motor Drivers to satisfy the design requirements of a variety of applications (<strong>Figure 2</strong>).</p>
<p align="center"><img alt="STMicroelectronics STSPIN Motor Control Infographic" src="/blog/Portals/11/ST%20STSPIN%20Motor%20Control%20Infographic_1.png" style="width: 600px; height: 776px;" title="STMicroelectronics STSPIN Motor Control Infographic" /></p>
<p><small><strong><em>Figure 2:</em></strong><em> The STMicroelectronics STSPIN Motor Control Infographic details the STSPIN Motor Drivers&#39; main applications.&nbsp;(Source: Mouser)</em></small></p>
<p>&nbsp;</p>
<div>
<h2>Conclusion</h2>
</div>
<p>Perhaps like me, you enjoy riding big Ferris wheels. On the other hand, you might be more like my daughter and consider it a crazy adventure well-worth avoiding. Regardless of your view, electric motors help make the world go round, and the precise spin and control provided by STMicroelectronics STSPIN Motor Drivers help us all to enjoy the ride.</p>
1162Move Over LEDs, Electric Motors Will Save the Planethttps://www.mouser.com/blog/move-over-leds-electric-motors-will-save-the-planetAllIndustrial,Motor Control,Power,Wide BandgapSat, 01 Dec 2018 05:59:00 GMT<p><img alt="" src="/blog/Portals/11/Keeping_Move%20Over%20LEDs_Theme%20Image.jpg" style="margin-left: 10px; margin-right: 10px; width: 200px; height: 133px; float: left;" title="" /></p>
<p>LED lighting is the poster child of environmentalists. And they do have a point. According to the U.S. Department of Energy, solid-state lighting is a highly energy-efficient technology, using 75 to 90 percent less energy, and lasting 25 times longer than traditional incandescent bulbs. The department says that widespread adoption could cut U.S. annual energy consumption by the equivalent of 44 large power stations. LEDs are exciting, trendy, and integrate seamlessly into wireless technology. Consumers, who buy lots of the LED bulbs, feel good about doing their part for the environment. What&rsquo;s not to like?</p>
<p>Perhaps little. Except that, while consuming a significant proportion&mdash;around a fifth&mdash;of U.S. electricity generation, lighting is far from the biggest energy consumer. That title goes to an indispensable, yet unexciting technology which works tirelessly behind factory shutters, hidden inside white goods, and lurking behind the floor panels of many autos and in a million other nooks and crannies, out-of-sight and out-of-mind of the public. Yet if we&rsquo;re serious about saving the planet, we need to turn our collective attention to the largest power consumer of all&mdash;the electric motor.</p>
<p>Exact numbers are hard to compile, but U.S. Department of Energy figures from a few years ago revealed that electric motors account for about two-thirds of industrial power consumption and around 50 percent of total U.S. electricity consumption. That&rsquo;s an incredible 2000TWh each year. Lighting comes in at a distant second, consuming about 19 percent. With numbers that large, even a one percent improvement in electric motor efficiency would eliminate the need for well over 200 large power stations.</p>
<p>While the environmentalists might have overlooked electric motors&rsquo; contribution to total energy consumption, engineers have been a little less tardy. To be fair, the techies&rsquo; motivation is not wholly altruistic&mdash;their customers constantly demand smaller, lighter, longer-lasting motors that are cheaper to run (over its lifetime, the electricity costs incurred by a motor are typically 20 times greater than the unit&rsquo;s purchase cost)&mdash;but the result is the same&mdash;greater efficiency leading to lower power demand. &nbsp;</p>
<h2>Honing electric motor design</h2>
<p>Motor efficiency is determined by how much power is supplied compared with the power the motor generates. For example, if it takes 2W of electrical power to generate 1W of motor power, the unit is 50 percent efficient. The difference (loss) is dissipated in overcoming things like mechanical friction, electrical resistance, and inductive losses. Through many iterations, engineers have honed their designs with innovations such as low-friction bearings, high-permeability magnets, and brushless (induction) firm factors. Contemporary motors boast efficiencies as high as 80 or 90 percent. But a few percent further improvement would have a significant impact on future electricity generating capacity.</p>
<p>Electronic power supplies have also played a major part in the motor revolution. A modern switch-mode power unit produces a three-phase sinusoidal input which in turn produces a rotating magnetic field pulling the device&rsquo;s rotor around without the use of loss-inducing brushes. In addition, the pulse-width modulation (PWM) superimposed on the base operating frequency enables precise <a href="https://www.mouser.com/applications/motor-control/">control</a> of parameters such as start-up current, torque, and slip. This precise control of parameters helps to further limit electrical losses.</p>
<p>Now engineers are taking things further:</p>
<p><strong>First, they are favoring high-voltage over traditional high-current designs</strong>. This is because nominal motor power is the product of supply voltage and current (V x A). Higher current pushes up the power but also demands the use of larger coils, increasing motor costs and size. <a href="https://www.mouser.com/applications/high-voltage/">High voltages</a> (of the order of 10kV) have the same effect on power but don&rsquo;t need expensive and heavy copper coils.</p>
<p><strong>Second, engineers are spinning motors faster</strong>. Primarily this is because it allows a more compact motor to do the same work as a larger, slower rotating machine, but it also has a small effect on efficiency. For example, increasing the operating frequency limits current ripple&mdash;an artifact of the initial rectified mains input and a source of loss&mdash;and electromagnetic interference (EMI). High-frequency operation also reduces torque ripple which can cause motor vibration, increased friction, and premature wear.</p>
<h2>WBG Semiconductors to the Rescue</h2>
<p>A challenge remains; the silicon MOSFETs and IGBTs used as the switching elements in electric motor power supplies are reaching their limits. The problem is fourfold:</p>
<p>&nbsp;</p>
<ul>
<li>The components&rsquo; are unable to handle the higher temperatures that come with more stressful operating conditions.</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>Their relatively low breakdown voltage limits how high engineers can push up input voltages.</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>Switching losses&mdash;caused by residual resistance and capacitance every time a transistor flips from &ldquo;ON&rdquo; to &ldquo;OFF&rdquo;&mdash;increase as the operating frequency climbs (negating efficiency gains elsewhere).</li>
</ul>
<p>&nbsp;</p>
<ul>
<li>Due to a long switching time, the devices have a relatively low maximum switching frequency.</li>
</ul>
<p>&nbsp;</p>
<p>A savior comes in the form of <a href="https://www.mouser.com/applications/wide-bandgap/">wide bandgap</a> (WBG) semiconductors. Materials such as gallium nitride (GaN) have a bandgap of 2eV to 4eV compared with silicon&rsquo;s 1eV to 1.5eV. A band gap is the measure of the energy required to free an electron for conduction in a semiconductor.</p>
<p>Because the electrons of GaN require more energy to escape from an atom and contribute to conduction than those of silicon, the semiconductor is much less prone to unscheduled switching caused by heat build-up rather than the deliberate application of a controlled voltage. GaN also exhibits a higher breakdown voltage than silicon, can switch in about one quarter of the time, and switching losses are around 10 to 30 percent those of a silicon transistor for a given switching frequency and motor current. Finally, because the electrons in GaN are able to move much more freely through the transistor&rsquo;s crystal lattice than those of silicon, GaN devices can flip much faster.&nbsp;</p>
<p>Commercial GaN solutions are now dropping in price, making them a viable option for cost-sensitive electric motor power supplies&mdash;particularly when the end-customer accounts for the motor&rsquo;s lifetime energy costs as well as its initial purchase price. But part of the take-up of this energy efficient technology will be driven by customer demand. LEDs are more expensive than conventional lighting, but when running costs and longevity are considered, they work out much cheaper than other forms of lighting. That&rsquo;s why consumers have adopted the technology. Now, it needs appliance manufacturers to sell the same advantages of the GaN-based electric motors in their washing machines and freezers. That way both the consumers and the environmentalists will really have a positive impact on the future environment of the planet.</p>
1132Ensuring the Electrical Safety of Powered Exoskeletonshttps://www.mouser.com/blog/ensuring-the-electrical-safety-of-powered-exoskeletonsAll,Connectors,EIT 2018: Generation Robot,Industrial,Medical,Motor Control,Power,Robotics,SensorsWed, 15 Aug 2018 05:01:00 GMT<p><img alt="" src="/blog/Portals/11/Molex_Robotic%20Gait%20Therapy.jpg" style="width: 250px; height: 136px; margin-left: 10px; margin-right: 10px; float: left;" title="" /></p>
<p>Driven by increased demand in the medical, industrial, and defense sectors, the global market for powered exoskeletons is expected to reach $2.8 billion by 2023&mdash;up from $300 million in 2017.</p>
<p>From improving the mobility of patients with spinal cord injuries to helping factory and construction workers lift heavy objects to enhancing soldiers&rsquo; capabilities on the battlefield, the benefits of bringing together the world of robotics and kinesiology are becoming hard to ignore. However, as is the case with virtually any wearable technology or electrically powered device, exoskeletons present inherent risks that designers and engineers must address to ensure the health and well-being of their users.</p>
<div>
<h2>Exoskeleton Design Challenges</h2>
</div>
<p>Many of the safety risks that are inherent in electronic products become significantly more important when the device in use directly interfaces with the human body for an extended amount of time. In the case of wearables, like earpieces or watches, problems such as overheating or electrostatic discharge are a concern. However, because the user has the option of manually removing the device (typically within a matter of seconds), the likelihood of any serious injury is almost nonexistent.</p>
<p>This is not always the case with exoskeletons, as they are often securely attached to or fully encapsulate a portion of the body, like an arm or leg. In such cases, during a malfunction that leads to overheating or a short circuit, for example, the user may be unable to quickly detach the system, thereby increasing the chance of injury.</p>
<p>Additionally, because many exoskeletons utilize high-torque servo motors to provide sufficient force for movements, a large power source is vital. Lithium-ion (Li-ion) batteries are an option for small exoskeletons that don&rsquo;t need to produce significant force; however, in many cases (especially in industrial applications) the exoskeleton must be connected to an external outlet and tethered. This connection inevitably exposes the user to high amperage and introduces the risk of electrical shock.</p>
<div>
<h2>Electrical, Thermal, and Biocompatibility Testing</h2>
</div>
<p>Electronic devices that interface with skin should not exceed an operating temperature of 37&deg;C, which is the core temperature of the human body. Temperatures over that can cause discomfort to the wearer and in severe cases can cause burning. As a result, many exoskeletons must meet medical electronics standards, which include design requirements to prevent overheating. This is also the case with hazards such as electrostatic discharge and exposure to radiation. &nbsp;</p>
<p>For many exoskeletons used in medical applications, the US Food and Drug Administration (FDA) Code of Federal Regulations (CFR) 21 addresses the risks and concerns regarding electrical shock, thermal burn, and biocompatibility. Part 890 of CFR 21 defines a powered lower-extremity exoskeleton as &ldquo;a prescription device that is composed of an external, powered, motorized orthosis that is placed over a person&rsquo;s paralyzed or weakened limbs for medical purposes.&rdquo; The directive states the following regarding the testing and safety of these devices:</p>
<ul>
<li>Elements of a device&rsquo;s materials that may have direct contact with the patient must demonstrate exact biocompatibility.</li>
<li>Appropriate analysis/testing must validate the presence of the correct levels of electromagnetic compatibility/interference (EMC/EMI), electrical safety, thermal safety, mechanical safety, battery performance and safety, and wireless performance, if applicable.</li>
</ul>
<h3>Batteries</h3>
<p>For exoskeletons that have their own power source, batteries are an area of concern that present one of the biggest safety risks to users. Thermal runaway is a problem that has been well documented relating to devices that use rechargeable Li-ion batteries. It occurs when an increase in temperature causes an exothermic reaction that results in a release of heat. This heat causes an increase in the rate of the exothermic reaction, which in turn releases more heat. Experiencing thermal runaway in the battery of an exoskeleton poses a serious risk.</p>
<p>In recent years, wearable system manufacturers have taken various steps to address safety risks associated with batteries. For instance, some systems utilize high-capacity disposable batteries as opposed to rechargeable Li-ions. Others are exploring advanced power management capabilities that monitor battery health and maximizes its use and life. A more recent development that has made its way into wearable devices with low-power consumption is the use of smart textiles, which harvest sunlight and gentle body movements to generate power internally.</p>
<h3>Wire Connectors</h3>
<p>Wire connectors are crucially important to the reliability and performance of wearable electronics; however, they have often been overlooked during the development and execution of a design because of their low cost and simplicity. This is particularly the case in exoskeletons, where more expensive integrated circuits and servo motors take precedent.</p>
<p>When examining failures in wearable electronic devices, examiners have discovered that one of the most commonly cited causes is a loss of contact between two conductors. Many times, this is the result of a failed wire connector. Exoskeletons often contain hundreds of connectors for components, including sensors, batteries, and circuit boards, among others. As all these represent a potential point of failure, the selection of proper connectors is critical.</p>
<p>The <a href="https://www.mouser.com/molex/generation-robot/">CP-3.3. Wire-to-Wire Connector System</a> from <a href="https://www.mouser.com/molex/generation-robot/">Molex</a> is an example of a product that is specifically designed for user safety in consumer electronics and industrial and medical wearable applications. The inertial lock on the receptacle housing helps ensure complete, low-insertion-force locking; minimizing the chance of failures and providing a tactile and audible click when mated. Additionally, fully polarized and color-coded plug and receptacle housings allow the use of multiple same-size-circuit connectors in a single application.</p>
<div>
<h2>Conclusion: Safety First</h2>
</div>
<p>In recent years, the market for powered exoskeletons in the medical and industrial sectors has grown immensely. While the benefits of these and other wearable electronic devices are becoming hard to ignore, designers and manufacturers must remain watchful of the potential safety risks they pose to users. While many innovative measures are being put in place to address the concerns associated with electronics that interface with the human body, the use of high-quality, high-reliability components, such as connectors and wires, has proved time and time again to be the most effective way to ensure overall success in product performance and reliability.</p>
608Get Past Conventional Wisdom When Selecting a DC Motor Typehttps://www.mouser.com/blog/get-past-conventional-wisdom-when-selecting-a-dc-motor-typeAll,Industrial,Maker,Motor ControlThu, 12 Apr 2018 05:01:00 GMT<p><img alt="" src="/blog/Portals/11/Schweber_Conventional%20Wisdom%20Selecting%20DC%20Motors%20Theme%20Image.jpg" style="width: 600px; height: 397px;" title="" /></p>
<p>The broad world of DC <a href="https://www.mouser.com/applications/motor-control/">motors</a> is divided into two basic categories: Brushed and brushless. The brushed motor has been around &ldquo;forever,&rdquo; figuratively speaking, and while billions of such motors in use prove it can work well, it has many well-known drawbacks. These include brush wear, electrical noise, low to moderate efficiency, controllability, and more.</p>
<p>Several decades ago, the brushless motor with its electrical commutation became popular. This was largely due to two developments: High-energy, permanent magnets and low-cost, effective power-switch devices (i.e., metal-oxide semiconductor field-effect transistors, or MOSFETs, and insulated-gate bipolar transistors, or IGBTs) for the coils. Pretty soon, it seemed as if brushed motors were relegated to low-end applications where high performance and reliability weren&rsquo;t priorities. Even the larger brushed motors in the range of hundreds of horsepower transitioned to true brushless designs or variable AC drives (a cousin of brushless), while smaller motors likewise often transitioned to the stepper-motor approach, another relative of the brushless motor. At some point, it seemed that brushed motors were only for low-cost, throwaway toys; window displays; and similar low-end applications.</p>
<p>Therefore, when a new product needs a DC motor, now the tendency is to think brushless, right? Probably so, but that would be a short-sighted approach. This was made very clear to me by the fascinating case study article entitled &ldquo;Every Drop Counts: Designing Motors to Optimize Home and Ambulatory Infusion Pumps,&rdquo; published in a January 2018 issue of <em>Medical Design Briefs</em>, in which an engineer at Portescap performs a motor-selection analysis for an infusion pump. This pump&mdash;motor, gearing, and pump mechanism&mdash;must be small, efficient, quiet, and reliable, as it sits on a pole near its user or while carried by a patient.</p>
<p>The author analyzes why the brushed motor is the best choice in this case, yet he also admits to its relative shortcomings versus the brushless motor. First, of course, he defines the flow-rate specification the assembly must achieve, which translates to torque and other basic performance specifications for the motor. He then qualitatively compares the characteristics of brushed, brushless, and stepper motors that meet these requirements. He also discusses the different gearing arrangements to the pump mechanism that the varying motor types would need, which is a major factor in the motor-selection process.</p>
<p>What impressed me was that the article did not say that the brushless was the best across all attributes of efficiency, compactness, lifetime, noise level, and reliability. In other words&mdash;though of no surprise&mdash;every design choice is a balance of tradeoffs made in the context of the dependencies among them. This is an engineering reality that is too often glossed over in a design review or discussion, yet it is the essence of the engineering process.</p>
<p>Such an article can teach old and new designers alike about focusing on more than simply matching a choice of options to the design priorities in a specific case. It can also clarify the need to be clear in any analysis when deciding on priorities, their weight, and their technical and dollar costs. In this case, the brushless and stepper motors had issues related to gearing and efficiency at the speed and torque levels required, which made them less-desirable choices even while the brushed motor showed some weaknesses regarding longer life.</p>
<p>Whether making decisions about motors or other key components, going with the &ldquo;obvious&rdquo; solution or with conventional, popular wisdom may not be the right choice. Step back and look at the numbers, tradeoffs, relationships, and compromises among parameters and performance with honesty, even as the case study showed for the infusion pump application.</p>
<p>&nbsp;</p>
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